Parts such as the Transmission: Bush,25x28x15, Gear,c-5, Sprocket,drive (1, Gear,c-2 are included in the Xrv650 Africa Twin 1988 (j) Austria Transmission parts fiche.
The lowest price component in this Transmission parts-list fiche is the Bolt Flang 6x12.
In this schematic the "Washer Spline 25x" is used most often.